Aircraft telephony communications systems are systems that allow an aircraft crewmember to place telephone calls through a ground based telephone system such as a Public Switched Telephone Network (PSTN). Thus a crew member may place telephone calls to ground based telephone customers or mobile telephone customers similarly as a person on the ground may place a call to another terrestrial user.
In present aircraft telephony systems there exists a radio link between the aircraft and the terrestrial PSTN system. One such link may be through a SatCom digital radio system that accesses terrestrial PSTN through communications satellites. Another possible link is through a conventional Flight Phone system as is employed in many commercial aircraft today, that may have either an analog or a digital radio link to the PSTN.
In order for a crewmember to place a telephone call through the PSTN, typically either the crewmember must remove his headset and utilize a separate telephone handset with a separate control apparatus for, for example, dialing a desired number, or he accesses the radio link to the PSTN through a Multifunction Control and Display Unit (MCDU). The MCDU is a common on-board system that performs many aircraft functions including flight plan management, communications, and the like. An MCDU has a display screen, which may be a CRT, LCD, flat panel display, or other suitable display and an associated control panel consisting of keypads and switches to select the various functions performed by the unit. To place a telephone call through a PSTN, a crewmember must select the telephone function on the MCDU and, using a keypad or other selection mechanism, usually on the MCDU, select or dial the desired number. After selecting the function and number, the crewmember must select the proper function (telephone) on an audio panel to initiate the call. Since the MCDU and the audio panel are usually not conterminously located, the crewmember is required to divert his attention unnecessarily from device to device, thus increasing the workload on the crewmember.
Consequently, it would be desirable to provide a system in which all, or virtually all, audio related functions may be controlled through a single control point, such as the audio panel.